JPS6133184B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a coated photoconductor for electrophotography with improved electrophotographic properties by adhering an alkali metal silicate and an alkaline earth metal or a group a compound of the periodic table to the surface of cadmium sulfide powder. and its manufacturing method.

Electrophotographic photoreceptors have various configurations in order to obtain predetermined characteristics or depending on the type of electrophotographic process to which they are applied. As representative electrophotographic photoreceptors, there are photoreceptors having a photoconductive layer formed on a support and photoreceptors having an insulating layer on the surface, which are widely used. The photoreceptor, consisting of a support and a photoconductive layer, is used for imaging by the most common electrophotographic processes, ie, charging, imagewise exposure and development, and optionally transfer. In addition, for photoreceptors equipped with an insulating layer, this insulating layer protects the photoconductive layer,
It is provided for the purpose of improving the mechanical strength of the photoreceptor or being applied to a specific electrophotographic process. Typical examples of photoreceptors having such an insulating layer or photoreceptors having an insulating layer in an electrophotographic process include, for example, U.S. Patent No. 2860048, Japanese Patent Publication No. 16429/1970, and Japanese Patent Publication No. 15446/1983. Japanese Patent Publication No. 46-3713, Japanese Patent Publication No. 42-23910, Japanese Patent Publication No. 43-247748, Japanese Patent Publication No. 19747-1974, Japanese Patent Publication No. 4121-1974, etc.

Electrophotographic photoreceptors are not only required to have predetermined sensitivity, electrical properties, and even optical properties depending on the electrophotographic process to which they are applied;
It is also important that the change characteristics of the usage conditions are not affected. However, photoreceptors using cadmium sulfide powder often have the following problems.

(1) Image density decreases significantly under high humidity.

(2) When a photosensitive plate is used repeatedly, the dark area potential decreases due to charging deterioration.

(3) Unevenness (roughness) occurs in the image quality of dark areas.

Conventionally, in order to solve this problem, methods were used to select a binder when producing a photoconductor or to mix a moisture-proofing agent into the photoconductor, but in the present invention, the photoconductor itself is treated to make it moisture-resistant. The main purpose of the present invention is to provide a photoconductor with excellent properties, image properties, etc., and a method for manufacturing the same.

The photoconductor according to the present invention has the general formula Me ₂ O・NSiO ₂ (where Me is K or
An alkali metal silicate represented by Na, N represents a positive number) is added thereto, and a compound selected from an alkaline earth metal compound and a group a compound of the periodic table is attached. It is something to do.

The improved properties for the photoconductor according to the invention are due to the alkali metal silicates and alkaline earth metal compounds or compounds of group a of the periodic table.

The alkaline earth metal compounds used in the present invention include compounds of or containing the elements calcium, strontium, barium, radium, beryllium, and magnesium, particularly organic acid salts of magnesium, barium, strontium, and calcium. , sulfates, nitrates, nitrites, etc. are suitable. Representative examples of such compounds include, for example,
(CH ₃ COO) ₂ BaH ₂ O, (C ₃ H ₅ O ₂ ) ₂ BaH ₂ O,
MgHC ₆ H ₅ O ₇・5H ₂ O, Mg (C ₃ H ₅ O ₃ )・3H ₂ O, Ca
(CHO ₂ ) ₂ , Ca (C ₃ H ₅ O ₃ ) ₂ 5H ₂ O, Ca
(C ₃ H ₅ O ₂ ) ₂・H ₂ O, Sr(C ₂ H ₃ O ₂ ) ₂ , Sr
(CHO ₂ ) ₂ , Sr(C ₃ H ₅ O ₃ )・3H ₂ O, MgSO ₄・
_7H2O , _MgSO4 , _CaSO4・_2H2O , _CaSO4・1/2
H ₂ O, CaSO ₄ , Ca (NO ₃ ) ₂・4H ₂ O, Ca
(NO ₃ ) ₂ , Ba (NO ₃ ) ₂ , Mg (NO ₃ ) ₂・6H ₂ O, Sr
(NO ₃ ) ₂ , Sr(NO ₃ ) ₂・4H ₂ O, Ba(NO ₂ ) ₂ , Mg
(NO ₂ ) ₂・3H ₂ O, Ca (NO ₂ ) ₂・H ₂ O, Ca
(NO ₂ ) ₂・4H ₂ O, and compounds of group a of the periodic table are compounds of or containing the elements boron, aluminum, gallium, indium, and thallium, and in particular aluminum, indium, Sulfates, nitrates, nitrites, aluminate compounds, organic acid salts, and selenate of gallium and thallium are suitable. Representative examples of these compounds include, for example, Al ₂ (SO ₄ ) ₃・18H ₂ O, Al ₂
(SO ₄ ) ₃ , Ga ₂ (SO ₄ ) ₃・18H ₂ O, Ga ₂ (SO ₄ ) ₃ , In ₂
(SO ₄ ) ₃・9H ₂ O, In ₂ (SO ₄ ) ₃ , Tl ₂ SO ₄ , AlTl
_{( SO4} ) ₂ , _12H2O , _NaAlO2 , _BaAl2O4 , Al
(NO ₃ ) ₃・9H ₂ O, Ga (NO ₃ ) ₂・nH ₂ O, In
(NO ₃ ) ₃・3H ₂ O, In(NO ₃ ) ₃・41/2H ₂ O,
TlNO ₃ , TlNO ₂ , Ga(Se ₄ O)・16H ₂ O, In ₂
(SeO ₄ ) ₃・10H ₂ O, Tl ₂ C ₂ O ₄ , Tl ₂ SeO ₄ ,
such as Tl ₂ C ₄ H ₄ O ₆ (n is a positive number).

The alkali metal silicate used in the present invention has a general formula of Me ₂ O・NSiO ₂ (where Me is K or
Na, N=positive number) is used. The alkali of this alkali metal silicate is
Na and K are preferable, and Li is not preferable because it has poor solubility in water, but also provides incomplete coverage. Also, the ratio of Me ₂ O to SiO ₂ , that is,
A particularly suitable range for N is 2.0 to 3.6. Those in this range are particularly excellent in transparency and adhesion to cadmium sulfide.

The production of the photoconductor according to the invention is usually carried out by mixing cadmium sulfide powder with an aqueous alkali metal silicate solution and then with a compound selected from alkaline earth metal compounds and group a compounds. By treatment with an aqueous alkali metal silicate solution, all or part of the surface of the cadmium sulfide powder is coated with an alkali metal silicate,
By adding compounds selected from alkaline earth metal compounds and group a compounds, these compounds are primarily deposited onto the alkali metal silicate coating. The concentration and amount of the alkali metal silicate aqueous solution may be set as appropriate, but the amount of the aqueous solution used is 0.001 to 0.1 wt of the alkali metal silicate as a solid component relative to the cadmium sulfide powder. %, particularly 0.005 to 0.05 wt%. Further, the amount of the compound selected from alkaline earth metal compounds and Group A compounds added is 0.0005 to 0.05 wt%, particularly 0.001 to 0.01 wt%, based on the cadmium sulfide powder in the aqueous solution containing the cadmium sulfide powder. %
It is preferable to make it so that

A more specific example of the method for manufacturing a photoconductor will be described.

Me ₂ O・nSiO ₂ in the cadmium sulfide powder
Add an aqueous solution of (Me: K or Na), stir this thoroughly with a stirrer, etc., then leave it for 15 to 16 minutes to coat the cadmium sulfide with the alkali metal silicate, and then add the alkaline earth metal compound or cadmium sulfide. Add and mix at least one of the group a compounds to an aqueous solution containing cadmium sulfide, then gently stir after adding the added alkaline earth or group a compound to dissolve the cadmium silicate sulfide suspension. Mix well with the suspension and then let it stand still to allow the action of these compounds to precipitate. Next, unnecessary ions remaining in the supernatant liquid and alkaline earth or group a element ions and anions that are not sufficiently attached are removed by washing with pure water. It is then thoroughly dried at a temperature of 50 to 150°C, sufficient to evaporate the moisture but not destroy the coating layer.

The photoconductive layer is usually formed by dispersing photoconductor powder in a binder. As the binder, for example,
Various resins are used, such as vinyl chloride resin, vinyl acetate resin, vinyl chloride/vinyl acetate copolymer resin, acrylic resin, urethane resin, polyester resin, epoxy resin, melamine resin, and silicone resin. The content of the resin forming the photoconductive layer is 100% of the photoconductive material.
It is preferably 0.5 to 50 parts by weight, particularly 5 to 20 parts by weight.

Regarding the photoconductor having an insulating layer, various ordinary resins can be appropriately used as the resin used to form the insulating layer. For example, resins such as polyethylene, polyester, polypropylene, polystyrene, polyvinyl chloride, polyvinyl acetate, acrylic resin, polycarbonate, silicone resin, fluororesin, and epoxy resin can be used.

Usually the thickness of the insulation layer is 0.1~100μ, especially 0.1
Set to ~50μ. The support is made of stainless steel.
It is formed from any material such as a metal plate such as copper, aluminum, or tin, paper, sheet, or resin film. The support may be omitted if necessary.

The thickness of the photoconductive layer depends on the type and characteristics of the photoconductive material used, but is generally 5 to 100 μm, particularly
Approximately 10 to 50μ is suitable.

Although the mechanism of action of the photoconductor according to the invention is not clear, the alkaline earth metal compound or Group A compound, in combination with the alkali metal silicate coating, improves the surface properties of the photoconductor, i.e., the barrier by charge control. It is thought that the electrophotographic properties are improved by the resistance adjustment function due to the reduction of the silicates and the formation of a protective coating by the silicate.

Examples will be specifically described below.

Example 1 CdS with Cl and Cu added as activators: Cu,
1 c.c. of a 1% K ₂ O.3.0SiO ₂ solution diluted with an appropriate amount of pure water was added to 100 g of a Cl photoconductor, and the mixture was thoroughly stirred with the photoconductor. After that, let it stand for 30 minutes, then 0.010
A solution of an appropriate amount of g(CH ₃ COO) ₂ BaH ₂ O dissolved in water was added, gently stirred, and then allowed to stand again. After that, approximately 70% of the supernatant liquid was removed and washed with water.
The coated photoconductor was washed and dried at 60°C to obtain a coated photoconductor. A photoconductive layer was formed on this photoconductor using an acrylic resin as a binder, and a 25 μm polyethylene terephthalate film was laminated thereon to obtain an electrophotographic photoreceptor. Next, positive corona charging was performed as primary charging, alternating current corona charging was applied as secondary charging, and at the same time, a light image was irradiated to expose the entire surface for evaluation. At this time, the contrast potential was 540V, which was good, and then this was adjusted to 100%RH.
When the contrast potential was measured again after being left in the room for one day, it was found to be 513V, and the retention rate was 95%, which was very good. Further, after this photosensitive plate was charged and exposed 10,000 times, the contrast potential was 520V, and the retention rate was 96%, which should satisfy this characteristic. Furthermore, when the image was evaluated, it provided a high-quality image with no roughness at all. At this time, at the same time, when untreated CdS was used as a photoconductor, the initial contrast potential was 560V, and the contrast retention rate after being left in 100% RH for one day was 70%, and there was no deterioration due to charging after 10,000 cycles. The subsequent contrast retention rate was 75%. Also, the image quality was a little rough.

Example 2 CdS: 1% K ₂ O to 100 g of Cu, Cl photoconductor.
3.3SiO ₂ solution was diluted with 0.8cc of appropriate amount of pure water and added.
Stir well with photoconductor. Then let it stand for 1 hour,
Next, a solution of 0.005 g of Al ₂ (SO ₄ ) _{3.18H 2} O dissolved in an appropriate amount of water was added, stirred, allowed to stand, washed, and dried. When this photoconductor was evaluated as a photoreceptor in the same manner as in Example 1, the contrast potential was
After being charged 10,000 times at 525V, the contrast retention rate was 93%, and there were no problems with image quality. Moreover, the moisture resistance retention rate was comparable to that of ordinary untreated CdS.

Example 3 CdS: 1% Na ₂ O to 100 g of Cu, Cl photoconductor.
The 2.5SiO ₂ solution was diluted with an appropriate amount of pure water and stirred and dispersed with the photoconductor. Thereafter, the mixture was allowed to stand for 45 minutes, and then a solution of 0.001 g of Ca(NO ₃ ) ₂ 4H ₂ O dissolved in an appropriate amount of water was added, stirred and left to stand, then washed and dried. When this photoconductor was evaluated as a photoreceptor in the same manner as in Example 1, the contrast potential was 500 V, and the image quality was excellent without roughness.

Example 4 Add 1% K ₂ O to 100 g of CdS; Cu, Cl photoconductor.
0.8 cc of 3.5SiO ₂ solution was diluted with an appropriate amount of pure water and added to the solution to be well dispersed with the photoconductor. After standing still, a MgSO ₄ .7H ₂ O solution of 0.004 g dissolved in water was added, and the mixture was stirred and left standing, then washed and dried. This photoconductor was evaluated as a photoreceptor in the same manner as in Example 1, and the contrast potential was
Contrast retention rate after charging deterioration at 500V for 10,000 times
It was 90%.

Example 5 CdS: 1% K ₂ O to 100 g of Cu, Cl photoconductor.
Dilute 3.0SiO ₂ solution with 0.9cc of pure water and add.
Well dispersed with photoconductor. After standing still, 0.010g
A solution of (CH ₃ COO) ₂ BaH ₂ O dissolved in an appropriate amount of water was added, and the mixture was stirred and allowed to stand, then washed and dried. This photoconductor was made into an electrophotographic photoreceptor having a function as a photoconductive insulating layer using a binder consisting of a polyvalent isocyanate compound and a polyol resin.

Next, after being charged by negative corona charging, a light image was irradiated and evaluated.

The contrast potential at this time is 450V and 100%RH
The contrast retention rate after being left in the container for one day was 80%.

In addition, when the image was evaluated, it provided a good image.
At this time, when untreated CdS was used as a photoreceptor, the initial contrast potential was 460V, and the contrast retention rate after being left at 100%RH for one day was 40%, and the image quality was a little rough. It was hot.

Claims (1)

[Claims] 1. General formula Me ₂ O on the surface of cadmium sulfide powder.
A compound to which an alkali metal silicate represented by NSiO ₂ (Me represents K or Na, and N represents a positive number) and is further selected from alkaline earth metal compounds and Group a compounds of the periodic table. An electrophotographic photoconductor comprising: attached thereto. 2 Cadmium sulfide powder and general formula Me ₂ O・NSiO ₂
(However, Me represents K or Na, and N represents a positive number)
An electrophotographic photoconductor comprising the steps of sufficiently mixing an alkali metal silicate solution represented by: and sufficiently mixing with an alkaline earth metal compound and a compound selected from Group a compounds of the periodic table. manufacturing method.